Enhanced resistance against bacterial wilt in transgenic tomato (Lycopersicon esculentum) lines expressing the Xa21 gene

Abstract

To enhance bacterial wilt resistance in tomato plants and simplify the protocol of Agrobacterium tumefaciens mediated gene transfer, parameters affecting transformation efficiency in tomato have been optimized. A. tumefaciens strain EHA101, harboring a recombinant binary expression vector pTCL5 containing the Xa21 gene under the control of the CaMV 35S promoter was used for transformation. Five cultivars of tomato (Rio Grande, Roma, Pusa Ruby Pant Bahr and Avinash) were tested for transformation. Transformation efficiency was highly dependent on preculture of the explants with acetosyringone, acetosyringone in co-cultivation media, shoot regeneration medium and pre-selection after co-cultivation without selective agent. One week of pre-selection following selection along with 400 lM acetosyringone resulted in 92.3% transient GUS expression efficiency in Rio Grande followed by 90.3% in Avinash. The presence and integration of the Xa21 gene in putative transgenic plants was confirmed by polymerase chain reaction (PCR) and Southern blot analyses with 4.5-42.12% PCR-positive shoots were obtained for Xa21 and hygromycin genes, respectively. Transgenic plants of the all lines showed resistance to bacterial wilt. T 1 plants (resulting from selfpollination of transgenic plants) tested against Pseudomonas solanacearum inoculation in glasshouse, showed Mendelian segregation.

Transgenic tomato plants expressing a wheat endochitinase gene demonstrate enhanced resistance to Fusarium oxysporum f. sp. lycopersici

“…Transgenic technology has been successfully used to protect crop plants against pests and diseases (Veluthambi et al 2003;Bhargava et al 2007;Afroz et al 2010). Durable resistance can be achieved by the expression and synergistic action of plant defense genes (Ouyang et al 2003;Fiocchetti et al 2008).…”

Transgenic Lines of Oryza Sativa (Basmati 2000) Expressing Xa21 Demonstrate Enhanced Resistance to Bacterial Blight

“…Broad-term resistance caused by Xa21 gene had opened the plethora for dicot in addition to monocots for bacterial diseases (Afroz et al 2011;Mendes et al 2009;Park et al 2010a, b;Peng et al 2008;Wang et al 1996). The objective of the present study was to investigate the role of Xa21 in developing BB stress tolerance in Basmati 2000 via Agrobacteriummediated transformation.…”

Genetic approaches for mitigating losses caused by bacterial wilt of tomato in tropical islands

“…This might be due to poor colonization ability of the antagonistic strains under different field conditions when compared to pathogen population (Yuan et al 2014). The use of transgenic crops (Afroz et al 2011) and genetically engineered microbes or avirulent mutants of Ralstonia solanacearum has also been suggested for tackling this disease (Kang et al 1995). But, cultivation of genetically modified materials may raise the ethical, environmental and health issues (Lemessa and Zeller 2007;Klümper and Qaim 2014).…”